Medina classification is the most popular angiographic classification of bifurcation lesions based on the presence or absence lesions at the three levels of branching (0,0,0 ) to (1,1,1). The popularity of this scheme is essentially due to its simplicity.

It can further be subdivided according to angle and size .Though there are three angles possible it is the angle of LM with LCX that matters most.

T shaped left main. Angle of LM-LCX is around 90 Degrees

Y shaped left main. Angle of LM- LCX is > 120 Degrees

Three types of Y according to size of branch vessel size.

Y1 Large left main divided two equal LAD, LCX.

Y2 Left main and one of its branches are equal

Y3 All three are equal diameter.

Here is a series of lectures on left main (Probably the best I guess !) from Dr.Boris Varshisky ,Hadassah University hospital Jeruselam.He critically discusses about the nuances of left main disease from pathology, technical and therapeutic considerations.

Spend some time on these videos , you should be able to learn about

Distribution of left main disease

The complexities in defining the true shapes of of left main ostia .(Ostial sharing between LCX and LAD ?)